College Physics

Teaching expansion of energy bang theory: discrete tight-binding model and its applications

SHEN Qing-hui, CHEN Bing

College Physics. 2023, 42(1): 1. doi:10.16854/j.cnki.1000-0712. 220310

Abstract ( 769 )

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Discrete tight-binding model is a very important one in physics. It captures the essential physics process by a simple interacting Hamiltonian. In this paper, the derivation of discrete tight-binding model from the wave equation of quantum mechanics is introduced. As an example, the result is applied on two common models in Solid State Physics. The discussions provide materials for students to study Solid State Physics further and also help students to read related scientific literature.

Motionanalysis of spring pendulum in uniform magnetic field

MENG Yong

College Physics. 2023, 42(1): 4. doi:10.16854/j.cnki.1000-0712.220312

Abstract ( 809 )

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Aiming at the background of the charged spring pendulum exerting a uniform magnetic field in the vertical direction, its kinematic equation is obtained by the method of Newtonian mechanics, and it is found that its swing plane is constantly rotating. At the same time, according to the different initial conditions, the kinematic equations in the horizontal direction are simplified into different curve equations, and then the trajectory characteristics of its motion are obtained.

Application of the residue theorem in topological phase transitions

MENG Ya, GUAN Xin

College Physics. 2023, 42(1): 7. doi:10.16854/j.cnki.1000-0712.220149

Abstract ( 672 )

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The residue theorem is an important theorem in the mathematical physics methods, which is a compulsory course of physics major in college． The teaching of this theorem in traditional teaching focuses only on the derivation of mathematical formulas and the transmission of mathematics thoughts, but it is rarely involved in its application in specific physical problems． Taking the problem of the topological phase transition in one-dimensional Su-Schrieffer-Heeger model as an example, one explains how to use the residue theorem to analytically obtain the expression of the second-order displacement and use this physical quantity to characterize the topological phase transition． Introducing the analysis examples of specific physical problems in the teaching process of the residue theorem can enable students to understand the physical connotation of mathematical theorems more deeply．

Derivation of Doppler effect formula based on relativity principle

CHEN Jing, ZHEN Chun-hua, XIAO Meng, HE Nan-lin

College Physics. 2023, 42(1): 11. doi:10.16854/j.cnki.1000-0712.220199

Abstract ( 1153 )

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The aim of college physics is to convey the idea of “connection” and “unity” to students, but the relation and unity between “relative motion” and “frequency change” are not explored deeply in many textbooks when derifying the Doppler effect formula. This paper starts from the definition of wavelength, based on the principle of relativity, using Galileo transformation formula to deduce and verify the Doppler effect formula of mechanical wave. The Doppler effect formula of electromagnetic wave is derived by Lorentz change formula. By deducing the Doppler effect formulas of mechanical and electromagnetic waves, it is revealed that the frequency variation of Doppler effect is actually measured in different inertial systems.

Application of laser-induced breakdown spectroscopy in experimental teaching of nuclear analysis

SUN Shao-hua, GAO Jian, LIU Tian-guang, REN Xian-xuan, HU Bi-tao, LIU Zuo-ye

College Physics. 2023, 42(1): 14. doi:10.16854/j.cnki.1000-0712.220284

Abstract ( 461 )

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In order to adapt the requirement of experimental teaching in nuclear physics and nuclear analysis, laser-induced breakdown spectroscopy (LIBS) is introduced to the experiments of nuclear engineering as an innovative demonstration experiment. Experimental measurement of LIBS spectra is performed during the interaction between nano-second laser pulses with different targets. The electronic temperature and density of laser plasma are extracted combining with theoretical analysis. The plasma density obtained from the characteristic spectral line of solo element is assumed to the plasma density of the mixed target, and the unknown spectral broadening parameter of Fe(I) is calculated.

Position sensitive plastic scintillator spectrometer based on Pixie-net digitizer

NI Lei, XIA Bo-long, LOU Jian-ling, XU Jin-yan

College Physics. 2023, 42(1): 19. doi:10.16854/j.cnki.1000-0712.220131

Abstract ( 425 )

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The energy spectrum of a 60Co source is measured by a 1-meter long plastic scintillator with a highly integrated Pixie-net digitizer. The position of the long plastic scintillator is calibrated by using the half-height position of Compton platform of 60Co sources. It is found that the difference between the calibration results and the actual position of radiation source is about 1~2 cm. The experimental results also show that the Pixi-net digitizer has strong ability to process the amplitude of a signal, and can replace QDC in the experiment of position sensitive plastic scintillator spectrometer.

Exploration of learning-centered college physics teaching in application-oriented institutes

ZHANG Li-hong, LEI Hui-ru

College Physics. 2023, 42(1): 25. doi:10.16854/j.cnki.1000-0712.220239

Abstract ( 514 )

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In order to change the ineffectiveness in current teaching, in this paper, a teaching mode is put forward to adapt to college physics in application-oriented institutes. This mode is focused on students’ learning and problems-driven, drawing lessons from splitting classroom and making use of online teaching. Teaching practice shows that this mode enhances students’ learning enthusiasm and improves classroom teaching quality.

An investigation on the feasibility of introducing temporal coupled-mode theory into the teaching of theoretical mechanics

HUANG Wan-xia, WANG Yi, XU Xin-sheng

College Physics. 2023, 42(1): 30. doi:10.16854/j.cnki.1000-0712.220150

Abstract ( 579 )

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Temporal coupled-mode theory, playing an increasingly important role in frontier scientific research, is widely used in Mechanics, Optics, Electricity and other related disciplines. Under the concept of combining teaching and research in undergraduate, the introduction of temporal coupled-model theory into Theoretical Mechanics is a matter of urgency. In this paper, combine the Lagrangian equation and the secular perturbation theory, the second-order differential equation of oscillator coupling is degenerated to the first-order differential equation, that is, the main equation of temporal coupled-mode theory. The study provides a scheme for the smooth acceptance of temporal coupled-mode theory by undergraduate students and has implications in terms of undergraduate quality development.

Exploration of ideological and political resources in electromagnetism course—take the permeation of dialectical materialism as an example

HUANG Gui-qin, ZHANG An-ran, YI Jing-hui

College Physics. 2023, 42(1): 35. doi:10.16854/j.cnki.1000-0712.220083

Abstract ( 685 )

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Electromagnetism course contains the dialectical materialism ideological elements. How to imperceptibly infiltrate the dialectical materialist viewpoint and method into the teaching process of electromagnetism is discussed through the combination of specific teaching cases, so as to promote the ideological and political connotation construction of electromagnetism course. This not only enables students to deeply understand and master the nature and law of electromagnetic phenomena, but also helps students to establish the world outlook of dialectical materialism and enhance their dialectical thinking ability.

Exploration and practice of online and offline mixed teaching mode of one body, two cores and four combinations in atomic physics

CUI Li-ling, LIAO Xiang-ping, ZHANG Guo-hua, ZHANG Dan, XIAO Jin

College Physics. 2023, 42(1): 42. doi:10.16854/j.cnki.1000-0712.220141

Abstract ( 486 )

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Relying on the construction of provincial first-class online and offline mixed curriculum of atomic physics, with the help of Erya general education online course platform of our university, in this paper the exploration and practice of the mixed teaching mode of atomic physics are actively carried out by using the learning wisdom teaching software. Through the process of online resource construction, teaching mode exploration and teaching mode practice, the teaching concept has been changed and the one body, two cores and four combinations mixed teaching mode have been innovatively constructed, which provide a certain reference for the reform of online and offline mixed teaching mode in local colleges and universities.

Pendant drop method to measure surface tension of waterdrops based on smartphone and Matlab at home

LU Yi-fan, JIN Zi-cheng, REN Wen-yi

College Physics. 2023, 42(1): 48. doi:10.16854/j.cnki.1000-0712.220196

Abstract ( 741 )

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An experiment of measuring surface tension of water droplets based on pendant drop method is developed by using a smartphone and Matlab software that can be used at home. The surface tension coefficient is calculated by taking a photo of water droplets with a smartphone and then using Matlab to recognize and calculate the edges. For various clarity cases, appropriate analysis and processing methods are presented, and testing results show that the method is stable and trustworthy. It is a typical case of post-epidemic experimental teaching of university physics at home.

Solution and visualization of wave functions in two-dimensional and three-dimensional infinite deep annular potential wells

WANG Yu-feng, FU Ke, WANG Yue-chao, SUI Lin-hong, JIANG Meng-yuan, FAN Ya-xi, LI Xi-bin

College Physics. 2023, 42(1): 55. doi:10.16854/j.cnki.1000-0712.220299

Abstract ( 1307 )

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The Schrodinger equation of two-dimensional and three-dimensional infinite deep annular potential wells is solved by the method of separating variables. The eigenvalue of the radial wave function is determined by the zero point of the cross product combination of the Bessel function. For the three-dimensional case, the analyticalsolution of the ground state wave function can be obtained. For the excited state wave function, the radial probability density distribution is given by numerical method. For the two-dimensional infinite deep annular potential well, the radial probability density distributions of ground state and excited state are given by numerical method.

Rainbow reappearance and characteristic analysis based on spray field

LI Wen-jun, GAO Chun-ping, GUO Chen-hui, PENG Li,

College Physics. 2023, 42(1): 60. doi:10.16854/j.cnki.1000-0712.220092

Abstract ( 447 )

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A correct understanding of the formation mechanism of rainbow can help students form a correct cognition of atmospheric optical phenomena. In this paper, a rainbow reproduction device is designed for students to build by themselves, and the influencing factors of rainbow reproduction are analyzed based on the device. It is found that it is easier to observe clear and bright rainbow when the droplet group with uniform distribution and large density is irradiated by the light source with good parallelism. Finally, the polarization characteristics of rainbow are demonstrated.

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